U.S. patent number 3,832,629 [Application Number 05/326,894] was granted by the patent office on 1974-08-27 for battery condition indicator.
This patent grant is currently assigned to ADAR, Inc.. Invention is credited to Edward Cernek, Jr..
United States Patent |
3,832,629 |
Cernek, Jr. |
August 27, 1974 |
BATTERY CONDITION INDICATOR
Abstract
A Battery Voltage Indicator is provided for indicating the
condition of the battery or dry cells or the like by providing
light flashes or a steady light from a light emitting diode when
the battery voltage is in the range for a usable battery. A
multi-vibrator is connected to derive its operating voltage from
the battery being tested and produces an output wave that
fluctuates above and below a given fraction of the multi-vibrator
battery voltage but having upper and lower levels each dependent
upon the battery voltage. A circuit for the light emitting diode is
provided which is energized when the voltage input is above the
predetermined level. Consequently the diode either emits light
continuously, flashes, or remains dark, depending upon whether the
battery is good, weak, or dead.
Inventors: |
Cernek, Jr.; Edward (Santa Ana,
CA) |
Assignee: |
ADAR, Inc. (Santa Ana,
CA)
|
Family
ID: |
23274193 |
Appl.
No.: |
05/326,894 |
Filed: |
January 26, 1973 |
Current U.S.
Class: |
324/436; 340/663;
340/691.1; 340/636.1; 340/636.15 |
Current CPC
Class: |
G01R
19/16542 (20130101) |
Current International
Class: |
G01R
31/36 (20060101); G01n 027/42 (); G08b
021/00 () |
Field of
Search: |
;324/29.5
;340/248B,248C,248D,249 ;320/48 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Smith; Alfred E.
Assistant Examiner: Hille; Rolf
Attorney, Agent or Firm: Knobbe, Martens, Olson, Hubbard
& Bear
Claims
What is claimed is:
1. A Battery Condition Indicator comprising in combination:
a pair of input terminals for connection to a battery, the
condition of which is to be tested;
an oscillator having an input connected to said terminals and
having as a voltage output an oscillation wave that is DC biased by
the voltage of said battery connected to said input;
an indicator circuit including a switch having a voltage responsive
control element and means coupling said control element to the
output of said oscillator, whereby the response of the indicator is
dependent upon the voltage attained by the oscillator output.
2. A Battery Condition Indicator as described in claim 1 wherein
the oscillator is an astable multi-vibrator with:
a load circuit; and
coupling means between a point in said load circuit and said switch
control element.
3. A Battery Condition Indicator as described in claim 2 wherein
the switch is a transistor with a relatively low saturation voltage
and the coupling between the switch control element and the
multi-vibrator circuit includes means for depressing the voltage
applied to the control element.
4. A Battery Voltage Indicator as described in claim 2 in which the
load circuit coupling to the switch control element comprises a
Zener diode.
5. A Battery Condition Indicator as described in claim 1 wherein
the switch comprises a transistor with a base, collector and
emitter with a base-current discharge resistor connected between
the base and the emitter, with a Zener diode coupling the base to
the oscillator output.
6. A Battery Condition Indicator as described in claim 1 wherein
the switch is responsive to a predetermined minimum voltage and a
lamp is included in the indicator circuit whereby the battery
condition is indicated by steady illumination from said lamp,
flashing light, or the lamp remaining dark dependent upon the upper
and lower voltage level output of the oscillator in relation to the
voltage at which the switch becomes responsive.
7. A Battery Condition Indicator as described in claim 6 wherein
the lamp is a light emitting diode connected in series with the
switch to said input terminals.
8. A Battery Condition Indicator, comprising:
a pair of input terminals for connection to a battery, the
condition of which is to be tested;
a voltage responsive circuit connected to said input terminals for
producing an oscillation wave that is DC biased by the voltage of
said battery, the maximum and minimum voltages of said oscillation
wave having a voltage level which is proportional to the voltage
difference between said input terminals; and
an indicator circuit including a switch which is actuated by a
predetermined voltage level, said switch coupled to said
oscillation wave, said indicator producing a signal whenever said
oscillation wave voltage exceeds said predetermined voltage level.
Description
SUMMARY OF THE INVENTION
In carrying out the invention in accordance with the preferred form
thereof, a multi-vibrator type of oscillator is provided having
power supply terminals which are the terminals to which a battery
to be tested is connected. For producing battery-condition
indication a lamp is provided in the form of a light emitting
diode, which is also connected in series with the input terminals,
and a solid state switch is connected in series with the light
emitting diode. The switch has a base coupled to a suitable point,
such as an intermediate point in a load resistor of one stage of
the multi-vibrator so that a variable voltage is applied to the
base of the solid state switch to turn the switch on or off
depending upon the voltage supply. Preferably the base is coupled
to the multi-vibrator load circuit by a Zener Diode so that the
switch is turned on only when the output voltage of the
multi-vibrator circuit is above a predetermined voltage.
The point at which the voltage is taken for the multi-vibrator is
so selected that the lower level voltage of the multi-vibrator
output is a large fraction, 9/10 for example, of the upper level
voltage, which approximates the battery voltage. Both voltages of
the multi-vibrator output wave depend upon and are substantially
proportional to the battery voltage. Consequently, for a good
battery the voltage applied to the solid state switch is high
enough so that the switch is always turned on and the light
emitting diode is illuminating steadily. However, for a battery
which is weak and still usable for a period of time the voltage
applied to the switch will be high enough to turn it on only during
the higher voltages of the multi-vibrator output wave so that the
light emitting diode is luminous intermittently and flashes. On the
other hand if the battery is dead or has such a low voltage that
satisfactory operation will not be obtained from it, the output
voltage wave of the multi-vibrator never becomes sufficiently high
to turn on the switch and the light emitting diode remains
dark.
A better understanding of the invention will be afforded by the
following detailed description considered in conjunction with the
accompanying drawing.
DRAWING
FIG. 1 of the drawing is a circuit diagram of an embodiment of the
invention; and
FIG. 2 is a graph illustrating the principle of operation.
DETAILED DESCRIPTION
As illustrated in FIG. 1 of the drawing, a battery 11, the
condition of which is to be indicated, is arranged for connection
to positive and negative terminals 12 and 13, respectively. The
terminals 12 and 13 serve as power supply terminals for an
oscillator 14 of the type that produces a direct-current output
wave which fluctuates between the upper and lower voltage levels.
In a preferred form of the invention the oscillator 14 takes the
form of an astable multi-vibrator including transistors Q1 and Q2,
shown as NPN transistors.
The collector-emitter circuits of the transistors Q1 and Q2 are
connected between the terminals 12 and 13 and cross coupled by
conventional resistor-capacitor coupling. As shown there are a
resistor R1 connected between the power supply terminal 12 and the
base of the transistor Q1, a resistor R2 connected between the
terminal 12 and the collector of transistor Q1, a resistor R3 in
the collector circuit of the transistor Q2, a resistor R4 connected
between the terminal 12 and the base of the resistor Q2, a resistor
R5 connected in series with the resistor R3 so that the resistors
R3 and R4 together form a collector load circuit for the transistor
Q2 with a junction terminal 15 utilized as the voltage output
terminal of the multi-vibrator 14. The transistors Q1 and Q2 have a
common emitter connection to the terminal 13 through an emitter
resistor R6.
For providing luminous indications of the condition of the battery
11, a lamp is provided preferably one having a very low current
demand such as a light-emitting diode D2. The light emitting diode
D2 is connected in series with a transistor Q3, shown as an NPN
transistor, between the terminals 12 and 13. The transistor Q3
serves as a voltage-responsive solid state control switch for the
light emitting diode D2.
The transistor Q3 has a base 16 coupled to the voltage output
terminal 15 of the multi-vibrator 14. Preferably means are provided
between the multi-vibrator output terminal 15 and the control base
16 of the transistor Q3 which depress the voltage applied to the
base 16, the switch Q3 being of the type which readily saturates at
a low voltage between its base and emitter.
In the arrangement illustrated, the coupling circuit between the
multi-vibrator output terminal 15 and the base 16 of the solid
state switch Q3 comprises a Zener Diode D1. A resistor R7 is
connected between the base 16 and the negative terminal 13,
providing a current path for any leakage properties that the Zener
diode may have had prior to the current breakdown. To augment the
current-limiting properties of the light emitting diode D2, a
current limiting resistor R8 is connected in series with the diode
D2 and the solid state switch 16.
The relative values of the resistors R3 and R5 are so chosen that
the lower level voltage of the multi-vibrator output is a
relatively large proportion of the upper level voltage, such as to
approximate 9/10 for example.
A Zener Diode D1 is chosen which has a breakdown voltage such that
the potential at the base 16 will rise above the potential at the
terminal 13 (plus the base-emitter junction voltage of the
transistor Q3) and remain above this level even for the minimum
level of voltage of the multi-vibrator output when the potential
difference between terminals 12 and 13 is high enough to represent
a good battery, but the voltage at the base 16 will not rise above
that at the terminal 13 at any time in the case of a dead
battery.
As illustrated in FIG. 2, in the case of a weak, but not dead
battery, the output voltage of the multi-vibrator circuit 14, the
voltage appearing at the terminal 15 is a fluctuating wave having
maximum and minimum voltages 18 and 19 fluctuating about a level
represented by a line 21. The Zener Diode D1 is chosen to have a
breakdown voltage approximating the voltage level 21 represented by
potential difference 20. In case of a weak battery the voltage at
the terminal 15 will fluctuate between the levels 18 and 19 with
the voltage applied to the base 16 fluctuating between the levels
22 and zero. The voltage supplied by the Zener Diode D1 at the base
16 cannot fall below zero. Consequently, the solid state switch Q3
is alternately in saturated and in non-saturated condition with the
switch turned on or off and the lamp D2 is intermittently luminous
to provide flashes.
On the other hand, in the case of a strong battery having a voltage
represented by the level 23, the output of the multi-vibrator at
the terminal 15 fluctuates between level 23 and 24 so that the
voltage remains constantly above the voltage level 21, the diode D1
conducts continuously and the switch 23 remains turned on
continuously to provide continuous illumination from the light
emitting diode D2.
Then in the case of a dead battery or one having an output voltage
which is so low that it is not satisfactory, the voltage at
terminal 15 never arises above a level 25, which is not above the
breakdown voltage of a diode D1, the transistor Q3 remains turned
off continuously and the lamp D2 remains dark.
The invention is not limited to the use of particular circuit
constants; however satisfactory operation has been obtained and
five to ten light flashes per second have resulted with the
resistor values approximately as follows: R1 1,000 ohms, R2 10,000
ohms, R3 10,000 ohms, R4 1,000 ohms, R5 1,000 ohms, R6 1,000 ohms,
R7 1,000 ohms, R8 2,000 ohms, and with capacitor C1 0.22 micro
farads and C2 0.22 MF.
A specific circuit arrangement has been illustrated and described
by way of example but it will be understood that the invention is
not limited to the embodiment illustrated and various modifications
will suggest themselves to those skilled in the art without
departing from the spirit of the invention.
* * * * *